My mom is pretty amazing with building things, my dad can't build a thing unless it is a computer, so when they wanted to redo the fence in their yard or build a bookcase or a bed frame, mom is the one who planned it out and bought supplies and put it together, only really using dad's assistance when she needed a taller body or extra hands (He isn't really stronger than she is either- unless its the jar that needs opening as she has arthritis in her hands).
Almost every time she goes to buy lumber she is treated poorly by sales people, she did find one sales person who treated her like a smart human being, and now she won't deal with anyone else.
When it comes to buying a car it is a similar thing, but she uses the "Let me call my husband" excuse and then negotiates a lower price over the phone. The best part is usually dad is just sitting quietly on the other end while she pretends they are having a conversation. It's sad she has to do this, but I still think it is hilarious that this has worked for almost 30 years.